Personally, the furthest I've seen endgame is Huhuran (and Razuvious, but he isn't a gear-dependent fight), but the effects they describe are clearly visible at easier instances as well. Back when we were trying to down Ragnaros or Hakkar or even 45-minute Baron for the first time, we buffed up like crazy and barely made it.

At our first successfull Ragnaros kill, I had Night Dragon's Breaths, Windblossom Berries, Mageblood, Wizard Oil, Flask of Supreme Power, a bunch of Greater Fire Protection potions, Major Mana Potions, Nightfin Soup, Blasted Lands buffs and even Juju Embers from Winterspring. Farming materials or cash for all that took several hours for each raid. Now, two tiers of gear later Ragnaros goes down with just a few Major Mana Potions.

At the time, I kept justifying the grinding to myself by the fact that we were still learning the encounter, and the buffs were covering up for any mistakes we might make. Increased survivablity meants that healers could spare that small bit of extra mana to keeping the tank alive and the extra DPS could down the boss just before the raid would start dropping like flies. We told ourselves that this was just a phase and it would get easier once we geared up some more and ironed out all the mistakes. We obviously did that and could phase out buffs, turning raiding into a profitable venture once again. So far so good.

However, the graph in the initial post does scare me. If top endgame continues to be balanced around all available buffs and even top-of-the-line gear from the final bosses isn't enough to slowly phase out buffs, then burnout is a very real possibility. A burnout on something you're supposed to be doing for fun. To relax. It's easy to justify doing some extra effort now to save effort later, but what if it never gets any easier? Especially when your grinding speed doesn't improve at the same pace (which is the case with healer classes and their raiding sets), it's very tempting to take the easy way out and to just buy your gold.

Personally, I think that every encounter should be tested with multiple tiers of gear. First, the gear you are supposed to be wearing when you start doing the instance. It should be very hard to progress, but not impossible. Secondly, with parts of the gear you get from the said instance. The encounter should be doable with proper focus and coordination. Finally, the encounter should be fairly easy once you've got most of the gear from the instance. No excessive buffing should be required at this point, and the relative lack of challenge should gently prod raiders towards the next encounter.

Of course, this kind of balancing assumes that there's always the next encounter. There isn't any when it comes to Kel'Thuzad now. Both Blizzard and the raiders knew that there wouldn't be anything to do after Kel'Thuzad. Blizzard wanted Kel to last until the expansion, so they needed to slow down raiding progress. They have tried hard tactics-based encounters before. They have tried straight-out DPS slugfests. They have tried resistance-based fights. And they have tried combinations. None of them worked for as long as Blizzard hoped. Determined raiders would analyze logs, crunch numbers, grind gear and practice until they cracked the encounters. So they used the one thing that even determined raiders wouldn't have enough: time. In other words, time required to farm buffs. If every attempt required a few hundred gold for each raider and enough instance runs to buff all of them, the raiders would not have any other choice than to limit the times they would attempt the encounter. In the end, not even that was enough.

So now Blizzard finds itself yet again in the vicious circle. There are several orders of magnitude more players than they have designers. Content will always be consumed much faster than it is generated. This applies to any form of entertainment, not just MMORPGs or games in general. Blizzard currently has several options. They could keep the status quo and accept that at any given time, they will have some amount of bored customers. They could make bleeding-edge content even more time-consuming to crack. However, this can pull the effort/reward ratio dangerously low and alienate customers who feel that they are not seeing any rewards (read: enjoyment) for their work. Yes, work. Work that you pay for. Customers might realize the absurdity of their actions and quit altogether.

Blizzard could increase the rate they produce content. There are two ways to do it. First way is to lower their standards of quality and just churn out more stuff with less polish. Blizzard knows that it would hurt both the game in the long run and more importantly the image of the firm itself. Blizzard has long been known as a firm that doesn't necessarily break new ground, but does everything better than the comptetition. Compromising quality would be suicidal.

The last option is most viable. Increase the volume of new content by hiring more designers. NCSoft, the company behind Guild Wars has an interesting solution: concurrent design teams. By interleaving releases they can keep the development cycle intact, yet churn out content at an increased rate. Imagine if Blizzard did the same. We could see stuff like the rumored South Seas expansion before Illidan bites the dust. And before Queen Azshara is on farm status the shores of Northrend would be at the horizon. Of course, hiring more designers costs money, which in turn cuts into the profit margin. However, WoW is the 500-pound gorilla of the MMORPG market. It is the undisputed market leader. And if Blizzard wants to keep it that way, they better have a big enough kitchen to keep feeding it.